Hydraulic pulling tool for use in wells



Sept. 117, 1957 E. l.. PoTTs 2,806,534

HYDRAULIC PULLING TOOL FOR USE I1N WELLS Filed April 30, 1952 5 Sheets-sheet 1 INVENToRf.

ATTORNEY Sept. 17, 1957 E. l.. FoTTs HYDRAULIC PULLING Toor. FOR USE 1N wELLs 5 sheets-sheet 2 Filed April 50. 1952 E L; POZJ v INVENTOR.

ATTORNEY Sept. 17, 1957 l HYDRAULIC PULLINGTOOL FOR USE` IN WELLS Filed April 30, 1952 5 Sheets-Sheet 3 .l L PO fs JNVENTOR.

'A roR/VEY ',ISept. 17, 1957 E. L.. Po'rTs 2,806,534

HYDRAULIC PULLING TOOL. FOR USE IN WLLS f; l. POZZJ .34 INVENTOR.

ATTORNEY Sept. 17, 1957 E. Po'r'rs HYDRAULIC PULLING Toor. FOR USE IN WELLS Filed April 3o. 1952 l 5 Sheets-Sheet 5 INVENToR //e/Zg ATTORNEY Unite States Patent O HYDRAULIC PULLING TOL FOR USE IN WELLS Ernest L. Potts, Houston, Tex., assignor to Cicero C. Brown, Houston, Tex.

Application April 3l), 1952, Serial No. 285,276

4 Claims. (Cl. 166-93) This application relates to a pulling tool and particularly to a pulling tool of a type adapted to pull liners, screens, stuck pipe or other stuck obects from a well.

This application is a continuation-in-part of my copending application Serial No. 139,267, filed January 18, 1950. My former application discloses a form of pulling tool composed essentially of a tubular stem, telescopically enclosed within a tubular sleeve defining one or more hydraulic cylinders about the stem, the stem carrying sealing members forming slidable seals with the cylinders which are reciprocable relative to the stem by hydraulic fluid introduced into the cylinders. The stern carries hydraulically actuated anchoring means on its upper end to anchor the stem to a well casing, While the sleeve carries grapple means on its lower end adapted to grasp the liner or other object to be pulled from the well. A J-type slot-and-pin connection is provided for releasably connecting the cylinder sleeve to the stem, so that the parts may be reversibly moved between active and inactive positions by a small amount of relative rotation between the stem and sleeve.

Such rotational types of connections are found to have certain disadvantages in operation, due particularly to the fact that the pulling tool is necessarily suspended from a long string of operating pipe which extends to the surface. The latter must, of course, be rotated at Vthe surface in order to effect the desired degree of rotation of the stem relative to the sleeve at a point which is often several thousand feet below the surface. -Due to the natural torsional flexibility of such a long string of operating pipe, it is often very difficult to determine at the surface when and if the requisite degree of rotational movement has been effected at the pulling tool and the operation of the tool may thereby be rendered uncertain and ineffective.

The present invention, therefore, is directed to improvements in the pulling tool of the former application which will overcome the described disadvantages.

A principal object of the present invention is to provide in a pulling tool of the type described, an improved form of releasable connection between the stem and sleeve which is actuated by relative longitudinal movements rather than by relative rotational movements.

A more specic object is to provide a form of releasable connection employing a cam means and a resilient cam follower means relatively movable between locking and release positions by relative longitudinal movement between the stem and sleeve members of the pulling tool.

Other and more specic objects and advantages of this invention will become readily apparent from the following detailed description when read in conjunction with the accompanying drawings which illustrate useful embodiments in accordance with this invention.

In the drawings:

Fig. 1 is a view showing the pulling tool inserted in a well and connected to a stuck pipe which is to be pulled, the parts being shown in the positions occupied at the completion of a pulling stroke;

firs

Figs. 2, 2A, and 2B, together, constitute a longitudinal quarter-sectional view of the pulling tool, showing the several parts in their respective positions when being lowered in a well and at the completion of a pulling stroke of the tool;

Fig. 3 is a cross-sectional view taken along line 3-3 of Fig. 2;

Figs. 4 and 5 are cross-sectional views taken, respectively, along lines 4-4 and 5-5 of Fig. 2B;

Fig. 6 is an enlarged longitudinal View, partly in section, of one embodiment of a releasable connection between the stem and cylinder sleeve members of the tool, showing the parts of the connection in the locked position;

Fig. 7 is a view similar to Fig. 6 showing the parts of the releasable connection at the point of release;

Figs. 8 and 8A, together, constitute a View generally similar to Figs. 2, 2A and 2B, but showing the positions of the parts during active pulling operations;

Fig. 9 is an enlarged view generally similar to Figs. 6 and 7 but illustrating another embodiment of the releasable connection, the parts being shown in the same stage of operation as that illustrated in Fig. 7;

Fig. 10 is a longitudinal, partly sectional, view of the releasable connection illustrated in Fig. 9, showing the parts of the connection in the locked position; and

Fig. 1l is a cross-sectional view taken along line 11-11 of Fig. 10.

Referring rst to Fig. l, the pulling tool comprises a tubular outer shell, designated generally by the numeral 10, and a tubular inner stem, designated generally by the numeral 1l which are arranged for relative telescopic movement. The lower end of shell 10 has connected thereto a suitable grapple means 12, which may be any one of the various conventional grappling or fishing tools commonly employed in wells. The particular grapple means, illustrated by way of example, is a conventional pipe spear which is adapted to be inserted in the bore of a tubular object 13, such as a pipe or liner which is stuck in a well bore 14 which is lined with the usual steel casing 15. Grapple means 12 is provided with the usual toothed slips 16 which are designed to be forced outwardly into engagement with the inner wall of the object by suitable manipulation of the spear in accordance with conventional practice, in order to thereby anchor shell 10 rigidly to the stuck object. The upper end of stem 11 which extends form the upper end of shell 10 is provided with an anchor means, designated generally by the numeral 17, which is designed to anchor the upper end of stem 11 to casing 15, and is connected to an operating pipe string 18, which extends to the surface.

Shell 10, as best seen in Figs. 2, 2A, and 2B, is composed of a series of tubular cylinders 19 which are coupled together by means of screw couplings 2t) each of which is provided with an inwardly extending annular shoulder 21, having a upwardly facing packing seat 21 thereon, which closely surrounds stem 11 to permit relative sliding movement between the stem and shell. The annular spaces above the shoulders between the couplings and the exterior of stem 11 form stuffing boxes 22 in which compressible packing 23 is installed, the packing being compressed by means of annular gland nuts 24 which are screwed into the upper ends of the stuffing boxes into compressive relation with the packing to urge the packing against seats 21 and to thereby expand it into fluid-tight sealing relation with the exterior of stem 11. The annular spaces between stem 11 and cylinders 19 extending longitudinally between each pair of couplings 20 define piston chambers 25, which are closed at each end by the inwardly extending portions of collars Ztl carrying sealing rings 23. A tubular sub 26 is screwed into the lower end of the lowermost cylinder 19 forming an extension of shell (Fig. 2B) and is provided at its lower end with an externally threaded tool joint pin 27 for connecting shell 10 to the grappling means 12. Sub 26 is provided withfanzaxial bore 28 for conductx ofuid.passinggthrough the. tool. An upwardly-facing, internal shoulder 29 (Fig 2B:) is provided. in; sub 261 toward its lower end.for pur-y A tubular sleevev 19a.v is connected by means of one of the couplingss-tdt-he.Y

posesto be described hereinafter.

uppermost one of cylinders 19 andisprovidedwith angularly spaced elongated slots 30 (Figs. l, 2 and 2A) cut in opposite walls of. the sleeve. extending longitudinally thereof from av point just below.. the. upper: endz ofv thisV sleeve to a point. somewhat. above the firstA ofi the couplings 20.

Stem 11 is composed of a. seriess'of generally. similar tubular sections, includingan upper section 32a and one or more intermediate and lower sections 32, connected` togetherv by collars.33;. Collars 3^3-whiclrl connect those of the stem sectionswhich extend through .the sever-al piston chambers 25 are providedontheirouter. peripheries with annular sealing rings 34which are seated on shoulders 35 and held in. compression. against the'shouldersby gland nuts 35a to thereby.- compress sealing rings34 into slidable sealing engagement with the inner Walls of cylinder 19 (Figs. 2A and.2B,)'. A. plurality of angularly spaced'radial ports 36 (Figs..2A,.2Band 4) are provided.

in the wall of anv orifice ring 32b co-axially positioned between the endsof stern sections 32 and communicate with passages 36a in collars 33 at points just above each of the sealing. rings 34 to provide communication between the respective piston chambers 25 and the axialA bore 37 which extends throughout stern 11 (Figs'..2A and 2B). The uppermost stem section. 32a isl provided with outwardly projecting lugs 38, equal in number toslots 30, adapted to project into slots 30 to provide a longitudinally slidable connection between stem.11 and shell 10, which servesalso to lockthestem and-cylinder against relative rotational movement (Fig. 2A).

Anchor means 17 (Figs. l, 2 and 3). is mounted on the upper end of uppermost stem section 32a and is com posed of an enlarged. generally cylindricalbody 39 having. an axial bore 40 therethrough. which registersrwith axial. bore 37'. An annular channel41- is cut circumferentially in the exterior of body 39 and. has seated in the inner end thereof a tubular. sleeve 42,v composed of rubber or other suitable resilient composition, which. is radially expandible and contractible by fluid pressure applied to1itsinner face through ports 43 in the wall of. body. 39. A plurality of slip segments 44, having. downwardly: facing. teeth 45, are mounted on the exterior surface of sleeve 42 and;

screwed over the lower end of extension 55. A nut 59.

is screwed on the exterior of extension 55 just above the end of cage 47 and forms an annular shoulder 6l). Cage 47 is provided internally at an intermediate point therein with a tapered valve seat 4S. A disk valve 51 havingl a downwardly tapering annular seat 52 about its periphery is mounted in the bore of the cage above the seat 48.

on a tubular stern 53 open at its lower. end which extends downwardly through the bore of cage 47. A plurality of ports 49 are provided in the wall of stern 53 intermediate.

its ends to afford communication betweenv the interior of the stem and bore 37` when valve 51 is in the open position and elevated relative to seat 48.. Seal rings 50 are annularly arranged in the wall ofcage. 47 below seat 48 to provide a iluid-tight seal between the wall of the cage and the exterior of stem 53. A collar 54 ismounted.

. shoulder 66. The upwardly exerted force `of spring 64 on the lower end of stern 53 and has a diameter such as to extend radially over shoulder 29 andover the lower end of cage 47. T-he collar 54 is provided with a plurality of channels 56 extending therethrough to permit passage of fluid between the portions of bore 28 above and below shoulder 29 when collar 54 is in contact with shoulder 29. A number of radial openings 57 (Fig. 2B) are provided in the wall of sub 26 to provide fluid communication between bore 28 andthe exterior of the tool. Additional series of. radial openings 58-58 (Figs. 2A and 2B) are provided in the walls of cylinders 19 adjacent their lower ends.

Arranged between sub 26 and extension 55 is a releasable connection, designatedv generally by the numeral 61, as shown in Fig. 2B and in enlarged views in Figs. 6 and 7. Connection 61 includes a wedge ring 62 slidably mounted on the exterior of extension 55 and provided about itsupper exterior periphery with an upwardly and inwardly beveled; wedging surface 63. Wedge ring; 62 is resiliently supported oni av coil compression spring 64 surrounding extension 55 and extending between the lower end of. wedge ring 62 and: shoulder 60. Spring 641actsgto urge wedge ring. 62 upwardly and to resist downward. movemento'f the wedge ring along; extension 55. The inner wall of sub 26, at a. point opposite wedgel ring. 62,.when. the latter is. in its. upper position, as seen in. Figs., 2B. .and 6, is provided with an annular. groove 65 having. its-upper end walltapering upwardly and inwardly towardtring 62 toprovidea cam shoulder 66. The angle of slope of shoulder 66 will usually be made somewhatgreater than. that of wedging surface 63 with respect to the longitudinal axis of the tool. At a point alongthe, inner wall of sub 26,v slightly above the outer end of shoulder 66, there is provided an upwardly and outwardly tapering cam surface 67, the inner ends of camshoulder 66 and cam surface. 67. being spaced apart by a portion72 of the inner. wallof sub 26. Rigidly secured to the wall of extension 55 above the upper end of. ring. 62. is an annular ball retainer 68 having an annular flange 69 extending downwardly betweenv ring 62 and groove 65. A- plurality of steel balls 70V are mounted in circum'ferentially spaced frusto-conical ball-retainer sockets 71 extending through flange 69, the outer diameter of` sockets 71 beingk somewhat less than the diameter of balls whereby to prevent the latter from. falling outwardly from the sockets. The engagement of the. balls. with surface 63 of ring 62 serves to prevent escape of theballs inwardly from sockets 71.

Balls.70. are dimensioned with` respect to the spacing between. ring.62 and groove 65 to span this space and to engage surface 63 and to extend into groove 65 below on ring 62 willnormally tend to hold balls 70in grooves 65, as illustrated. particularly in Fig. 6, by virtue of the wedging action of wedging surface 63 on the balls. In this position, it will be seen that cam shoulder 66 acts as. an upper stop for the balls against which the ballsy Will be thrust by the wedging actionof ring 62 thereby locking. stem 11= against upward movement relative to sub 26. It will also be evident that in order to release this connection stem 11 must be pulled upwardly relative. to shell 10 to bring the rounded surfaces of balls 70 against the upwardly tapering surface of cam shoulder 66. When the upward force thus applied to stem 11' exceeds the opposing force of spring 64, the slope of cam shoulder 66, acting against balls 70 and thence upon wedging surface 63, will force ring 62 downwardly suiiiciently to allow balls 70 to move upwardly along wedging surface 63 and radially inwardly sufficient to clear the inner end. of shoulder 66, whereupon continued upward pull on stern 11 will draw-the balls upwardly over wall portion 72., (Fig. 7'.) As; soon as balls 70 move past walli portion 72. to a. position opposite tapered surface 67, the pressure of theballs on wedge ring 62 will be released allowing springy 64 to expand4 to move the wedge ring upwardly relative to flange 69 in order to retain the balls in socket 71. Stem 11 will now be free to move upwardly relative to shell 10.

To again lock stem 11 to shell 10, the stem will be lowered to bring the portions of balls 70 which project outwardly from sockets 71 against cam surface 67 which, by reason of its downward and inward taper will force the balls inwardly against wedge surface 63. The downward force of stem 11 applied through the wall of sockets 71 against the balls will force wedge ring 62 downwardly against the pressure of spring 64 sufliciently to allow the balls to move downwardly past the inner end of cam surface 67 and over the adjacent portion 72 of the inner wall of sub 26 to again enter groove 65 where the balls again become engaged between wedge surface 63 and cam shoulder 66 to re-establish the locking connection between the stem and shell. Wedge ring 62, spring 64, balls 70 and ball retainer 68 comprise a cam follower which cooperates with cam shoulder 66 and cam surface 67 to provide the described releasable connection between the stern and cylinder elements of the pulling tool.

The operation of the above described pulling tool is as follows: The tool will be connected to pipe string 18 by connecting the upper end of stem 11 thereto through the medium of box 46. Grapple means 12 will be connected to the lower end of shell by means of pin 27, and the assembled string loweredv into well bore 14 through casing 15. At this stage, which is illustrated particularly in Figs. l to 6, outer shell 10 will be locked in the elevated position relative to stem 11, as illustrated in Figs. 1 to 6. In this position shoulder 29 will be thereby pulled upwardly against collar 54 whereby to urge valve stem 53 upwardly and thereby raise valve 51 oft' of seat 48. Opening of the valve will permit fluid which may be, and usually is, present in the well and which must be displaced to allow the tool to move freely down the well, to liow through openings 57 and channels 56 into the bore of stem 53 and thence -through ports 49 and the open valve into bore 37 of stem 11. Or well uid may also be displaced upwardly through appropriate passages in the grapple means into bore 28 of sub 26, passing through channels 56, and thence through openings 57 back into the annular space between the exterior of the tool and casing 15. Grapple means 12 will then be engaged with the object, such as pipe 13, which is to be pulled, to thereby anchor outer shell 10 firmly to the object. The attachment of a grapple means 12, such as the conventional pipe spear illustrated in Fig. l, is entirely conventional and well known, and is accomplished ordinarily by limited rotation of the operating string which will cause slips 16 to be expanded into tight gripping engagement with pipe 13. Since shell 10 will now be firmly anchored to the stuck pipe, an upward pull may now be applied to stem 11 sufficient to pull balls 70 out of groove 65 as previously described and to thereby release stem 11 for upward movement relative to the shell.

Lugs 38 will move upwardly in slots 36 until they strike the closed upper ends of the slots, whose length will ordinarily be made to approximately the full length of the stroke of the pulling tool, thereby fully extending the tool to the position at which pulling action is initiated. Figs. 8 and 8A illustrate the positions of the several parts of the tool at this stage of operations. It will be seen that sealing collars 33 are now in the upper ends of piston chambers 25 and tha-t the check valve 51 yat the lower end of stem 11 will be closed since the lower end of valve stem ,53 will be also drawn upwardly out of Contact with shoulder 29, and will be moved to the closed position by its own weight or by the pressure of iiuid in bore 37 of the stem.

Hydraulic iiuid, of any suitable character, such as ordinary drilling mud, will now be pumped down the interior of the operating pipe into the bore of stem 11.

Since the latter is closed at its lower end by vvalve 51, pressure will be built up in the fluid, a portion of which will flow through ports 43 and will act against lthe inner face of sleeve 42 expanding the latter outwardly under the pressure of the fluid. The resulting expansion of sleeve 42 will drive the slip segments 44 radially out-I wardly into tight gripping engagement with the wall of casing 15 (see Figs. l and 8), thereby firmly anchoring the upper end of stem 11 to the wall of the casing. At the same time, the uid introduced into bore 37 of the stem will flow through ports 36 and 36a into the several piston chambers 25 and will exert hydraulic pressure therein between sealing collars 33 and the upper end closures formed by collars 20 and stuiiing boxes 22, and will produce relative axial movement between these seals. Since stem 11 is now firmly anchored to casing 15, the pressure will act upwardly against the upper ends of the piston chambers, and as these are rigidly connected to shell 10, the latter will be forced in the upward direction relative to stem 11 and the upward force thus applied will be transmitted to grapple means 12 and its connected fish and pull the latter upwardly in the well bore. The upward movement of shell l@ will draw cyl inders 19 up over sealing collars 33, and at the completion of the stroke of the tool, the sealing collars will be at the bottoms of the piston chambers (Figs. 2A and 2B). Openings 58 permit escape of any fluid which may be trapped between the piston chambers below sealing collars 33.

As the cylinders approach the upper end of their strokes, shoulder 29 will again come in contact with collar 54 and upon slight additional upward movement of shell 10 will push valve stem 53 upwardly to open the check Valve. This will immediately relieve the fluid pressure in the tool, the uid escaping from the lower end of bore 37 and owing through the now opened ports 49 into the bore of valve stem 53 and thence through channels 56 and ports 57 into well bore, or through bore 28 and fluid passages in the grappling means. The release of pressure will become immediately evident through a drop in pump pressure at the surface, thereby providing means for signalling completion of the pulling stroke. At the same time, the relief of pressure in the tool will also relieve the expansive pressure on resilient sleeve 42, thereby allowing slip segments 44 to retract from their gripping engagement with casing 15 and placing the toolv and the attached iish in condition to be withdrawn from the well, if the fish has been suficiently loosened.y f

As the upward movement of the shell approaches the end yof its stroke, cam surfaces 67 will move upwardly past balls 70 of the locking means, the balls moving downwardly relative thereto and being forced inwardly as previously described, until they pass downwardly past wall portion 72 and again enter groove 65 to again lock the stem to the cylinder in the inactive position.

If the stuck pipe has not been loosened sufficiently by a single stroke to be withdrawn from the well bore, the previously described operations may be repeated as often as necessary to fully release the pipe.

Figs. 9 to l1 illustrate another embodiment of a releasable connection between the stem and the shell which may be operated by relative longitudinal movements between the stem and the shell.

In this embodiment the connection elements on the inner wall of sub 26 are substantially identical with those employed in the embodiment previously described and are identified by the same numerals. Wedge ring 62 is, however, replaced by a collar 75 which is rigidly secured to the upper end of extension 55 and has an external diameter such as to form a close sliding lit with the inner wall of sub 26. An annular groove 76 is provided in the outer periphery of collar 75 and positioned to be opposite groove 65 When the parts are in the inactive position. A snap ring 77 constructed of spring steel is mounted in groove 7.6 and has a nominalVv external diameter substantially equal to the external diameter of collar 75. Snap ring 77 is held within groove 76 by means of a threaded retainer ring. 76a which is screwed over the upper end of collar 75 to form the upper end wall of groove 76. Snap ring 77 isprovided at one point with a split 78 (Fig. 11), which allows the ring, when unconstrained, to resiliently expand to a somewhat larger diameter than the external diameter of collar 75 so as to project, radially into groove 65 (Fig. 10). The outer upper edge of snap ring 77 is bevelled to provide a wedge surface '79' having a slope generally complementary to that of cam shoulder 66. The lower outer edge of snap ring 77 is rounded -to form a cam surface 80. Snap ring '77 and collar 75 constitute the cam follower in this embodiment of the releasable connection between the stem and cylinder elements.

Fig. 10 shows` the connection members in the locked position wherein snap ring 77 has expanded to project into groove 65 and its wedgev surface 79 is engaged by cam shoulder 66 to thereby hold the stem locked to the shell. When suiiicient upward force is applied to stem 11 a wedging force will be applied between surfaces 79 and 66. The slope of these surfaces will produce an inward radial component which will be exerted to compress snap ring 77 sufficiently to allow it to be pulled past portion 72 until it is opposite surface 67 when it may again expand. Stem 11, will, however, be thus freed for upward movement relative to the shell. To relock the parts, downward. movement of the stem will bring rounded surface 80 on the bottom of the snap ring into engagement with cam surface 67 which will compress the snap ring sufficiently to pass portion 72 and allow stem 11 to move downwardly until the snap ring is again opposite groove 65 where` it will again expand and lock the stem to the cylinder.

It will be evident that although the releasable connections are described above as employed with one particular type of pulling tool, these connections have more general application and may be employed in other types of tool for releasably connecting two parts which are telescopically engaged.

It will be understood that the number and dimensions of the hydraulic cylinders which may be employed may be varied as desired, depending upon the pulling force and length of stroke desired. Various other alterations and changes may be made in the details of the illustrative embodiment within the scope of the appended claims without departing 'from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. A hydraulic pulling tool for use in wells, comprising, an inner tubular stem member and an o utersleeve member connected for relative axial' movement, means for connecting said stem member to a pipe extending into a Well, anchoring means mounted onv the stem member for anchoring it to the well wall, anchoring means mounted on the sleeve for anchoring it to an object to be pulled from the well, lonigtudinally spaced annular sealing elements mounted on the respective members and extending circumferentially between the members to define a hydraulic cylinder between said sealing` elements, a releasable connection between said stern member and sleeve member comprising a radially inwardly projecting cam shoulder on the inner wall of said sleeve member, a movable cam follower mounted on the exterior of said stem member andV resiliently urged into compressive engagement with the lower face of said shoulder to normally holdA said stem and sleeve members against relative axial movement, said shoulder andfollower being cooperatively shaped to permit said follower to be drawn past said shoulder by longitudinal pull applied by said pipe to said stem member exceeding the resilient engaging force exerted between said shoulder and follower with the sleeve member secured to saidy object, and means for introducing hydraulic uid from the pipe through said stem member 8 into saidcylinderto effect relative longitudinal movement between the stem member and the sleeve member when anchored respectively to the well wall and to said object.

2. A hydraulic pulling tool according to claim 1, wherein said cam follower comprises a split snap ring constructed ofV resilient metal and surrounding said stem member.

3. A hydraulic pulling tool for use in a well, comprising, an inner tubular stem member and an outer sleeve member connected for relative axial movement, means carried by the members for respectively anchoring the stem member to a well wall and the sleeve member to an object to be pulled from the well, longitudinally spaced annular sealing elements mounted on the respective members andl `extending circumferentially between the members to define a hydraulic-cylinder between the sealing elements, a releasable connection between said stem member and said sleeve member comprising a radially inwardly projecting cam shoulder on the inner wall of said -sleeve member, a wedge ring surrounding said stem member, spring means urging said wedge ring upwardly along the stem member, a plurality of angularly spaced balls supported on said stem member in compressive engagement between opposing surfaces of said wedge ring and said shoulder, `said balls being movable past said shoulder by longitudinal pull on said stem member exceeding the resilient engaging force exerted between the shoulder and the wedge ring, and means for introducing hydraulic uid through said stem member into said cylinder to eiect relative longitudinal movement between said stem and sleeve members when anchored respectively to the well wall and to said object.

4. A hydraulic pulling tool for use in wells, comprising, an inner tubular stem member and an outer sleeve member connected for relative axial movement, means for connecting said stem member to a pipe extending into a well, anchoring means mounted on the stem member for anchoring it to the well wall, anchoring means mounted on the sleeve member for anchoring it to the object to be pulled from the well, longitudinally spaced annular sealing elements mounted on the respective members and extending circumferentially between the members to define hydraulic cylinders between said sealing elements, a releasable connection between said stem member and said sleeve member comprising a cam shoulder element onone of said members and a movable cam follower element mounted on the other of said members and resiliently urged into compressive engagement with the shoulder element to normally hold said stem and sleeve members against relative axial movement, said shoulder and follower elements being cooperatively shaped to permit one of said elements to be drawn past the other by longitudinal pull applied by said pipe to said stem member exceeding the resilient engaging force exerted between said shoulder and follower elements with the sleeve member secured to` said object, and means for introducing hydraulic fluid from the pipe through said stem member into said cylinders to eliect longitudinal movement between the stem member and the sleeve member when anchored respectively to the well wall and to said object.

References Cited in the file of this patent UNITED STATES PATENTS 1,441,097 Laughlin Jan. 2, 1923 1,801,673 Knox Apr. 2l, 1931 1,803,732 Schaffer May 5, 1931 1,852,250 McCullough Apr. 5, 1932 2,295,961 Meyer Sept. 15, 1942 2,393,962 Ashton et al. Feb. 5, 1946 2,462,994 Price Mar. 1, 1949 2,507,127 True May 9, 1950 2,537,413 Lawrence Jan. 9, 1951 FOREIGN PATENTS 493,471 Great Britain Oct. 10, 1938 

